scholarly journals Silver nanoparticles as an antimicrobial agent: A case study on Staphylococcus aureus and Escherichia coli as models for Gram-positive and Gram-negative bacteria

2017 ◽  
Vol 63 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Eman Zakaria Gomaa
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Silver Nanoparticles ◽  
Antimicrobial Agent ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative

Survival of some non-starter bacteria in naturally ripened and enzyme-accelerated Cheddar cheese

1988 ◽  
Vol 55 (4) ◽  
pp. 597-602 ◽  
Author(s):  
Lydia Bautista ◽  
Rohan G. Kroll
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Enterococcus Faecalis ◽  
Enzyme System ◽  
Cheddar Cheese ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Ripening Period ◽  
Gram Positive Bacteria

SummaryEffects of the addition of a proteinase (Neutrase 1–5S) and a peptidase (aminopeptidase DP-102) as agents for accelerating the ripening of Cheddar cheese on the survival of some non-starter bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coliand aSalmonellasp.) were studied throughout a 4-month ripening period. The enzymes were found to have no significant effect on the survival of the Gram-positive bacteria but some significant effects were observed, at some stages of the ripening period, with the Gram-negative bacteria in that lower levels were recovered from cheeses treated with the enzyme system.

scholarly journals Green Synthesis of Silver Nanoparticles Using Novel Launaea Procumbens Leaves Extract and Screening Its Antibacterial Activity

2021 ◽  
Author(s):  
Sanjay Ratan Kumavat ◽  
SATYENDRA MISHRA
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Gram Negative Bacteria ◽  
Zone Of Inhibition ◽  
Gram Negative ◽  
Green Synthesized Silver Nanoparticles ◽  
Launaea Procumbens

Abstract Plants are emerging as a cost-effective and ecofriendly method for green synthesis of nanoparticles. The plant extract Launaea procumbens was used as a reduction agent in the green synthesis of silver nanoparticles. UV-Visible spectroscopy, HR-TEM, SAED, FE-SEM, EDAX, DLS, and FT-IR were used to study the green synthesized silver nanoparticles. UV-Vis spectroscopy of a prepared silver solution revealed maximum absorption at 435 nm. The synthesized silver nanoparticles were found to be spherical in shape with a size in the range of 24.28 to 31.54 nm. DLS analysis was used to determine the size of the green synthesized silver nanoparticles, which showed outstanding antibacterial action against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, as well as Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Gram-positive Bacillus subtilis had a maximum zone of inhibition of 20 mm, Staphylococcus aureus had a zone of inhibition of 19 mm, and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa had zones of inhibition of 13 mm.

scholarly journals Paper modified with ZnO nanorods – antimicrobial studies

2012 ◽  
Vol 3 ◽  
pp. 684-691 ◽  
Author(s):  
Mayuree Jaisai ◽  
Sunandan Baruah ◽  
Joydeep Dutta
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Aspergillus Niger ◽  
Zno Nanorods ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Tissue Paper ◽  
Gram Positive Bacteria ◽  
Lighting Conditions

Paper with antimicrobial properties was developed through in situ growth of ZnO nanorods. The targeted application for this type of paper is in health centers as wallpaper, writing paper, facemasks, tissue paper, etc. The paper was tested on three model microbes, Gram-positive bacteriaStaphylococcus aureus,Gram-negative bacteriaEscherichia coliand common airborne fungusAspergillus niger. No viable bacterial colonies or fungal spores could be detected in the areas surrounding test samples of the antimicrobial paper. Gram-negative bacteriaEscherichia coliwere found to be inhibited in an area that is 239% and 163% the area of the paper sample under different room lighting conditions, i.e., halogen and fluorescent lamp illumination, respectively. For Gram-positive bacteriaStaphylococcus aureusthe zones of inhibition surrounding the paper samples are 102% and 70%, and forAspergillus niger, 224% and 183% of the sample area, under similar lighting conditions.

scholarly journals SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF SILVER NANOPARTICLES STABILIZED BY CITRATE ANIONS

2020 ◽  
Vol 2020 (60) ◽  
pp. 127-135
Author(s):  
Liliya BAZYLYAK ◽  
◽  
Andriy KYTSYA ◽  
Ilona KARPENKO ◽  
Olena KARPENKO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Cell Walls ◽  
Colloidal Silver ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Vis Spectroscopy

Widespread use of synthetic antimicrobial drugs leads to the development of antibiotic resistance of pathogenic strains of microorganisms. Therefore, today researchers are very interested in drugs based on nanoparticles of metals, in particular silver and copper, which have antibacterial, antifungal and antiviral activity. One of the reasons for the high interest of researchers in AgNPs as an antimicrobial agent is the significantly lower toxicity of AgNPs compared to Ag+ ions. High antibacterial efficiency of silver nano¬particles is achieved due to their developed surface, which provides maximum contact with the environment. In addition, such nanoparticles are quite small and are able to penetrate cell membranes, to affect intracellular processes from within. Therefore, the aim of this work was to obtain concentrated colloidal silver solutions stabilized by citrate anions, which simultaneously provide satisfactory stabilization of colloidal silver solutions and are non-toxic, as well as to investigate the antimicrobial action of synthesized AgNPs. The solution of citrate stabilized silver nanoparticles (AgNPs) have been obtained via the reaction of reduction of silver nitrate by hydrazine in alkaline medium in the presence of sodium citrate. AgNPs were investigated using transmission electron microscopy (TEM) and UV-vis spectroscopy and the particles size and particles size distribution (PSD) were determined. It was observed that obtained AgNPs are mainly spherical shape. It was found that the mean diameter and PSD of AgNPs determined using TEM and UV-vis spectroscopy are close and equal to 14 and 5 nm and 15 and 4 nm respectively. Obtained solution was concentrated by evaporation at 70 C under reduced pressure up to achievement of AgNPs concentration equal to 200 mg/L. On the base of comparison of optical properties of initial silver sol and concentrated solution the minority of agglomeration of AgNPs was statement. At the same time AgNO3 test showed no change of UV-vis spectrum of concentrate that points on the absence of reducing agent in the solution; this fact indicate that hydrazine was eliminated from during the evaporation of initial AgNPs solution and obtained concentrate did not consist the toxic impurities. Antimicrobial activity of obtained citrate stabilised AgNPs against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacterium was tested using disk diffusion method. It was found that AgNPs shown significant bactericidal effect even at low (25 mg/L) concentration as well as some higher efficiency against Gram-negative bacterium. There was also a slightly higher antimicrobial activity of the drug against gram-negative bacteria Escherichia coli compared with gram-positive bacteria Bacillus subtilis, due to the different structure of cell walls. In particular, the walls of gram-positive bacteria consist mainly of peptidoglycan (murein), and gram-negative bacteria have cell walls with a layer of peptidoglycan and an outer membrane with a lipopolysaccharide component, which is not present in gram-positive bacteria. Based on the studies, it can be concluded that the proposed method of synthesis of AgNPs is suitable for obtaining highly concentrated silver sols. This method of synthesis is simple in hardware design, scalable, and the resulting colloidal solutions are stable and do not contain harmful impurities. Therefore, due to the high antibacterial activity of citrate-anion-stabilized AgNPs against certain types of gram-positive and gram-negative bacteria, it can be recommended for the manufacture of bactericidal drugs for biomedical purposes.

scholarly journals Green Synthesis, Antioxidant and Antimicrobial Activity of Silver Nanoparticles Using Gnetum africanum Extracts

2021 ◽  
pp. 1-7
Author(s):  
I. M. Uneze ◽  
J. O. Otonko ◽  
A. K. Adigun ◽  
S. J. Adebayo
Keyword(s):  
Escherichia Coli ◽  
Aqueous Solution ◽  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Leaf Extract ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Positive Bacteria

The synthesis and application of nanoparticles is an important area of research that is gaining attention recently. In this recent project, we report the synthesis of silver nanoparticles, AgNP using aqueous solution of silver nitrate and Gnetum africanum leaf extract (reducing agent). The synthesis of AgNP was achieved by mixing aqueous solution of silver nitrate (70ml, 15.75mM) with a solution of Gnetum africanum leaf extract 100 ml) in a reaction flask and allowed to stand for 24 hours in a dark cupboard. A color change from light brown to yellowish brown was observed which indicated that synthesis of silver nanoparticles took place. The presence of AgNP was ascertained using UV-vis spectra analysis and absorption at 442 nm showed the presence of AgNP. The antioxidant assay of both the synthesized AgNP and the leaf extract was determined using DPPH. Antimicrobial activity was conducted using three different organisms which were Staphylococcus aureus, Escherichia coli and Pseudomonas respectively. The antioxidant results using DPPH scavenging ability of AgNp showed that at concentrations of 2mg/ml,1mg/ml and 0.1mg/ml, the percentage inhibition  of  DPPH  by AgNp was 61.69, 53.06 and 38.31 respectively and that of Gnetum africanum leaf extract was 81.32, 78.49, and 58.29 respectively at the same concentrations using Ascorbic acid as a standard. The antimicrobial activity of both the synthesized AgNps and Gnetum Africanum Leaf extract using one gram positive bacteria (Staphylococcus aureus) and two gram negative bacteria (Escherichia coli and Pseudomonas) revealed that the synthesized AgNps showed lesser activity than Gnetumafricanum leaf extract for both the gram positive bacteria (Staphylococcus aureus) and gram negative bacteria (Pseudomonas) and (Escherichia coli). From the above findings, it can be observed that Gnetum Africanum Leaf extract reduced Ag+ to Ag0 and also both the synthesized AgNps and the Gnetum Africanum Leaf extract showed reasonable antioxidant activity against DPPH and antimicrobial activity against the tested microorganisms. This implied that both samples have medicinal values.

scholarly journals Bacteriological Profile, Antibiotic Susceptibility Pattern and Predictors of bacteremia among Children with Bloodstream Infection

2021 ◽  
Author(s):  
Samina Nazir Chaki ◽  
Levina Msuya ◽  
Deborah Mchaile ◽  
Michael Johnson Mahande ◽  
Ronald Mwitalemi Mbwasi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Bloodstream Infection ◽  
Antibiotic Susceptibility ◽  
Klebsiella Pneumonia ◽  
Gram Negative Bacteria ◽  
Susceptibility Pattern ◽  
Gram Positive ◽  
Antibiotic Susceptibility Pattern ◽  
Gram Negative

Abstract Background: Bloodstream infections are major causes of morbidity and mortality among children in Sub-Saharan countries. This study aimed to determine the prevalence of bacteremia, etiological agents’ antibiotic susceptibility pattern and predictors of bacteremia among children with bloodstream Infection.Methodology: This hospital-based cross-section study involved children aged two months to thirteen years. All children meeting the inclusion criteria during the study period were enrolled. All consenting parents were interviewed via a questionnaire to collect data, followed by a thorough physical assessment and venipuncture was done to collect blood samples. Data were analysed using SPSS version 23.Results: Among 242 study participants, 154(63.6%) were male and blood cultures were positive in 37(15.3%). Gram-positive and gram-negative bacteria constituted 32(80%) and 8(20%), respectively. The frequent pathogen found was Staphylococcus aureus 25(62.5%), followed by Enterococcus spp. 4(10%), Escherichia coli 4(10%), Pseudomonas aeruginosa 3(7.5%), Streptococcus pyogenes 3(7.5%) and 1(2.5%) Klebsiella pneumonia. The majority of bacterial isolates showed high resistance to commonly used antibiotics in the study area. Predictors of bacteremia were severe malnutrition, hydrocephalus, hyperglycemia, lethargy and BSI with no foci of infection. Conclusion: Prevalence of bacteremia was 15.3%. Gram-positive bacteria were more prevalent than gram-negative bacteria. Staphylococcus aureus and Escherichia coli were the prevalent isolates causing BSI. Effective antibiotics for both gram-negative & gram-positive organisms are imipenem, meropenem and piperacillin-tazobactam followed by amikacin; vancomycin & clindamycin for gram-positive organisms. To curb the growing antimicrobial resistance that we see in this and other studies, continuous antimicrobial stewardship is necessary, else we risk failing to treat BSI.

scholarly journals Analysis of antibiotics administration in diabetic ulcer patients at Panembahan Senopati regional hospital Bantul

2021 ◽  
Vol 8 (8) ◽  
pp. 3782
Author(s):  
Adnal K. P. Husein Putra ◽  
Sri Sundari
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Foot Ulcer ◽  
Diabetic Foot Ulcer ◽  
Antibiotic Administration ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Diabetic Ulcer ◽  
Gram Negative ◽  
Gram Positive Bacteria

Background: This study provides an overview of diabetic ulcer infection, antibiotic susceptibility patterns, the most common types of antibiotics, factors influence in antibiotics administrations, and verifying the guideline used of antibiotics.Methods: The research used descriptive analysis combined with interviews. The study was starting from February-March 2021. Eighty-six diabetic ulcer patients were selected considering the inclusion and exclusion criteria. We interviewed seven doctors.Results: 71 bacterias were found with a gram-negative bacteria count of 80.3%- higher than gram-positive bacteria (19.7%). The most common gram-negative bacteria found are Escherichia coli (12.7%) and show the most heightened sensitivity with imipenem (80.7%), while cefuroxime and trimethoprim-sulfamethoxazole show the highest resistance (64.9%). The most common gram-positive bacteria found are Staphylococcus aureus (14.1%), and vancomycin shows the most heightened sensitivity (100%), while penicillin shows the highest resistance (71.4%). The most common single antibiotic administration was ceftriaxone, as well as a combination of two antibiotics, namely ceftriaxone and metronidazole.Conclusions: Escherichia coli was the most gram-negative bacteria, which has the highest sensitivity with imipenem, while Staphylococcus aureus was the most gram-positive bacteria, which has the most heightened sensitivity with vancomycin. The most common single antibiotic administration was ceftriaxone, as well as a combination of two antibiotics, ceftriaxone and metronidazole. Factors that influence antibiotics administration are patient condition, susceptibility testing, training, and advice from colleagues. Every doctor uses different guidelines for diabetic foot ulcer.

scholarly journals Gram Negative Bacteria (Escherichia coli) Win Against Gram Positive Bacteria (Staphylococcus aureus) in The Same Media

2021 ◽  
Vol 4 (2) ◽  
pp. 113
Author(s):  
Neisya Intan Cahyaningtyas Agung Putri ◽  
Ramadhani Ramadhani ◽  
Eddy Bagus Wasito
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Doubling Time ◽  
Bacterial Culture ◽  
Agar Plate ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Significant Difference

Introduction: Biodiversity of the microorganism in Indonesia lead to the large amount of patient with infection. Human can get infected in two different place, with different kind of bacteria that cause the infection. This may lead to bacteremia without knowing which bacteria type whose causing it, either the Gram positive or Gram negative bacteria, whereas the treatment of this two types of bacteria are different. The aim of this study is to determine the doubling time of the Gram positive and Gram negative bacteria when they are grown in the same lesion and the kinds of bacteria that we need to eliminate first.Methods: Staphylococcus aureus and Escherichia coli bacteria were used as samples in this study. Bacterial culture in nutrient broth with 0.5 OD turbidity were mixed then incubated in incubator with 35˚C. Every one hour within 24 hour, 0.01 ml of bacterial culture was taken in serial dilutionover time, varying between 106 – 1012, . It was then planted in nutrient agar plate with droplets technique. After it had been incubated for 24 hours, we counted the Colony Forming Unit per ml (CFU/ml) to time, then the doubling time of the bacteria. The result were then compared between the Staphylococcus aureus and Escherichia coli group.Results: Two tailed t-test result of the doubling time between Staphylococcus aureus dan Escherichia coli was < 0,05 (p=0,000) wich means that there is significant difference of the doubling time between Staphylococcus aureus (24,35 ± 2,23 munites), and Escherichia coli (18,37 ± 0,50 minutes). When grown in the same media, Gram positive bacteria (Staphylococcus aureus) had slower doubling time than Gram negative bacteria (Escherichia coli) as much as 1.32 times.Conclusion: In bacteremia with two possible kinds of bacterial suspect, we need to eliminate the Gram negative bacteria first.

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